The Bent Bonds/Antiperiplanar Hypothesis (BBAH) is a collaborative research project between Ghislain and Pierre Deslongchamps.

The BBAH is a conceptually novel orbital model for rationalizing the conformation and reactivity of organic molecules containing various types of unsaturation. The BBAH is based on the Slater-Pauling bent bond model (tau bond, 𝜏 bond) and the antiperiplanar hypothesis, a modern stereoelectronic concept, to describe electronic delocalization in unsaturated systems.

left: 𝜏 bonds (bent bonds); right: σ/π bonds

To date, the BBAH model has been successfully applied to the following:

  • conformational analysis of alkenes and carbonyl compounds
  • conjugation and aromaticity
  • electrocyclic reactions
  • Diels-Alder reaction
  • sigmatropic alkyl and hydrogen shifts
  • walk rearrangements
  • cyclooctatetraene chemistry
  • high-temperature isomerization of polycyclic aromatic compounds
  • reactivity at anomeric centre of furansides and pyranosides
  • stereocontrolled nucleophilic addition to α-chiral ketones and aldehydes

The development of the BBAH and its various applications are in peer-reviewed publications, and are in the process of being authored as educational articles in BBAH Blog posts.